Four years on from the start of the civil war, Syria is a country in ruins.

And the ones most badly affected by the conflict are its children, youngsters like three-year old Asma whose home is a rotting tent.

When she turns four this year, she should be starting school, but like her two older brothers, she will stay in the cramped shelter instead.

One of 11 million Syrian's who have been forced to leave their homes since the start of the civil war, Asma was in her mother's belly when they fled Homs under shelling and gunfire.

More than 70 members of her extended family were killed in one night.

Born in a refugee camp in Lebanon's Bekaa Valley, she and her siblings are now part of what a new report has called a “the lost generation” - robbed of their childhood, their education and their future.

Four years since the start of the bloody conflict, the shocking study has gauged the devastating long-term effects that generation will have on the country's future.

According to the findings, it could cost Syria's economy a massive £1.5 billion every year after the war ends for the duration of their working lives.

Victim: Anas

These children will cost the country 5.4 per cent of its GDP every year through lack of education and skills and their earning potential for the future leaves most of them at risk of life-long poverty.

Asma's mother Huda is desperate as she tries to provide for her children in these horrific conditions.

She said: ”Here in Lebanon we are safe from war, but life is very hard. Living in this tent is no life at all.

“We have no space, no dignity, and we are not able to make enough money to live.

"We survive on support from NGOs and the UN but it is not enough, there are too many people here who need help.”

This is Huda's third year living in miserable conditions in the tent with her three young children and her husband – every year they swelter in the hot summers and freeze during the winter snowstorms.

When survival is hard, education is not a priority, creating a whole generation of uneducated, unskilled adults of the future.

The new document - commissioned by charity Save Children - comes days after a joint NGO report criticised the UN for failing four million Syrians who have been forced to leave the country and cross into neighbouring lands.

Victim: Anas

It revealed that three million Syrian refugee kids are out of school and estimates over 6,000 teachers have been killed so far in the war.

Prior to the conflict, school enrolment rates were almost 100%, but they have dropped, as low at 6% in some heavily contested areas such as Aleppo.

The direct cost of replacing damaged, destroyed or occupied schools and training replacement teachers in Syria could exceed £2 billion alone after the conflict is resolved.

But Huda's children who have reached a refugee camp are, in some ways, the lucky ones.

Many of those who remain in the country are not only missing out on an education but being forced into child labour in dangerous jobs, just to stay alive.

Eight-year old Anas works in a motorbike repair shop. He dropped out of school after the first grade, and has not been back since.

He said: “We fled our home and lived in an old Roman cemetery. There was no school in the area

“I wish I could go back to school. I keep telling my mother that I want to go back to school but she always says tomorrow and then she postpones it. I like school more than working here.”

But while foreign aid continues to fall short, the future for children like Asma and Anas will remain bleak.

Huda added: “I am worried for my children. I look at children in Europe and America and all the opportunities they have to learn and be happy, and I wish I could create the same for my children. They deserve it too.”